Tuesday, January 30, 2007

An internal change to allow compilation using gfortran : the fortran r1mach routine which was included in the file functions/cont.f has been replaced by a C version (with appropriate cfortran macro) in the new file functions/r1mach.c. This should have no effect visible to users. The analogous change has already been made in v12.

Thursday, January 25, 2007

Binbin Zhang asks a question about using chatter in xselect. The chatter command is handled through the xpi gtcom2 call but was not defined in xselect.key and xselect.kw so was rejected as an unknown command. Modified these files so that chatter is now recognised. However, all output from xselect is at chatter=5 so unless we make changes to the xselwrite calls we can either see all the output or none of it.

Roncarelli et al. calculate the thermal and kinetic SZ signals from a large cosmology simulation and look at correlations with the soft X-ray signal.

Bolton et al. use strong lensing data to replace the surface brightness with mass density in the fundamental plane relation for ellipticals and show that the variance decreases and the tilt is removed implying that early type galaxies are an homologous sequence varying in mass-to-light ratio.

Mathews & Brighenti describe how cosmic rays produced by an AGN generate the cavities and radio sources seen in X-ray emitting clusters.

Thursday, January 11, 2007

Koester et al. create a catalog of 13,823 clusters of galaxies in the SDSS. The algorithm used is described in another preprint.

Collister et al. use a neural network to generate a photometric redshift catalog of over one million luminous red galaxies from the SDSS. The training set is a 15,000 galaxy spectroscopic catalog from Cannon et al.

Done & Nayakshin argue that the AGN soft excess is more likely to be due to absorption in a wind than reflection from a disk since the latter, unlike the former, requires fine tuning of the ionization state.

Temi et al. find extended far IR emission from ellipticals using Spitzer and interpret it as due to cold gas buoyantly transported from a reservoir in the core.

Corasaniti et al. note that a new generation of big telescopes and very high resolution spectrographs will be able to measure the change in redshift in quasar absorption line systems over a ten-year baseline and hence constrain models for the cosmic expansion history.

Wednesday, January 10, 2007

Stephane Paltani reports an array overwrite warning message when running rbnrmf on JEM-X response matrix. It turns out to be due to these matrices having a starting channel of 0 for the EBD extension but 1 for the MATRIX extension. This shouldn't be a problem except that rbnrmf was incorrectly using the number from the EBD extension when rebinning the data from the MATRIX extension. Fixed this as version 5.0.1.

Coble et al. present results on 28.5 GHz radio sources in 90 cluster fields. They find 9 times more sources in cluster cores than in the outskirts which themselves are 3 times overdense in sources relative to the field.

Wednesday, January 03, 2007

There are bugs in both v11 and v12 which prevent correct convergence for some datasets with low counts in both the source and background files. The v11 fix is available as 11.3.2ab and the v12 fix will be available shortly.

However, it appears that the eventual best fit is still biased - this is likely a statistical rather than computational problem. The model seems to be be biased systematically below the data so a possible approach is to add another term which pushes the total number of model and data counts to be the same.

Liddle reviews approaches to the problem of selecting between competing models.

Takei et al. claim a detection of the WHIM in the direction of X Comae both in absorption using the XMM RGS and emission using EPIC.

Nevaleinen et al. look at XMM observations of 4 clusters with previous claims of soft excesses and conclude that there are still significant calibration problems at low energies in either the MOS or PN (or perhaps) both which make it impossible to conclude whether or not there is a soft excess.